The sigY gene product, a putative extracytoplasmic function (ECF) sigma factor, is the focus of the proposed work. In Bacillus subtilis, ten alternative sigma factors have been studied and play a role in the control of sporulation, motility, nutrient uptake, and some stress responses. Genes for seven additional alternative sigma factors were identified upon completion of the B. subtilis genome project based on the homology of their predicted protein products to a new family of sigma factors. Members of this new family of ECF sigmas regulate extracytoplasmic functions of biomedical interest such as the periplasmic heat shock response, osmotic adaptation, exotoxin production, and antibiotic synthesis/resistance. One of the seven ECF sigma genes identified in B. subtilis, sigY, encodes the sigmaY polypeptide, sigmaY initiates transcription from a template bearing the sigY promoter region, providing the first biochemical evidence of its activity as a sigma factor and suggesting that sigY may be autotranscribed. In collaboration with the Helmann laboratory at Cornell University the biochemical activity of sigmaY has been exploited in preliminary Run-off transcription/Macroarray Analyses (ROMA). This approach promises to yield rapid results in defining members of the sigmaY regulon (Specific Aim 1). Interestingly, a sigmaY-dependent reporter construct is expressed in minimal but not complex media, suggesting that a nutritional signal(s) governs the expression of the sigmaY regulon. This signal(s) is predicted to inhibit the activity of a membrane-bound anti-sigma factor encoded within the sigY operon. Therefore, the role of the sigY operon gene products in the control of sigY expression and sigmaY activity will be studied (Specific Aim 2). It is anticipated that identification of members of the sigmaY regulon, together with analysis of the gene products encoded in the sigY operon, will lead to testable hypotheses regarding the importance of sigmaY in the physiology of B. subtilis (Specific Aim 3). The proposed work promises to extend our knowledge of ECF function and promotes active collaboration with the Helmann laboratory that pioneered work on ECF sigmas in B. subtilis as well as ROMA methodology, there by providing an outstanding research program in which to train underrepresented minority students (Specific Aim 4).